Thanks for the previous help, but I just realized this doesn't answer all 
my problems. Specifically, the system is multi-homed (using 
/etc/ifaliases). I would need to ping using each address as the source 
address of each ping. But I don't see a way in 'ping' to do this. Am I 
missing a ping option, or is there some other command I use to change the 
source address for ping?